This invention relates to an apparatus for use with a multi-phase bath for cleaning, degreasing, plating, or pre-plating treatment of a substrate or similar type use. More particularly, it relates to an apparatus wherein items to be immersed in or exposed to lower phases of a multi-phase bath may enter and exit the lower phase fluid of the bath without coming in contact with the upper phase liquid.
A wide variety of industrial processes such as cleaning, degreasing, plating, or various pre-plating processes require the treatment of an article or material by immersion in a liquid bath. Liquid employed in such treatments are often highly volatile and frequency produce hazardous vapors. To minimize costly losses from evaporation as well as to minimize the exposure of operating personnel to harmful vapors, it is often desirable to maintain such liquid baths in a covered state, at least covered to an extent consistent with operating requirements. However, the use of a solid cover over such a liquid bath results in the disadvantage of obstructing the viewing of the internal portions of the bath as well as interfering with physical access to the interior portions of the bath. To avoid these disadvantages, some prior art processes provide a fluid covering over the bath. Typically, the fluid covering is a relatively non-hazardous, low-volatility, transparent liquid, such as water, which is of lower specific gravity and non-miscible with the lower liquid of the bath. Such a two phase fluid system permits easier viewing and more convenient access to the internal portions of the bath. One problem encountered in the use of such a two layer bath is that an article to be immersed in or exposed to the lower liquid, must also come in contact with the surface liquid. In some processes this may be permissible or even desirable. However, in other processes it is not desirable, for example, in instances where contact with the surface liquid may adversely affect the surface of the article being treated and prevent or inhibit the wetting action or other action of the lower liquid.
In such processes where it is desirable to immerse articles in the lower liquid without contact with the surface liquid it has generally been necessary to completely remove the surface liquid from all or a portion of the bath each time a working operation is started, and replace the surface liquid each time the working operation is discontinued. Manual removal of the surface liquid requires the expenditure of time and labor. Thus, it is desirable to provide a process and apparatus wherein this operation may be performed automatically. Furthermore, the complete removal of the surface liquid may result in the exposure of an unnecessarily large surface of the lower liquid with a consequent evaporative loss and the possible exposure of operating personnel to hazardous vapors. For this reason, it is desirable to provide a process and apparatus wherein the surface liquid may be conveniently and completely removed from a selected minimum area, the size of which is consistent with operating needs.
Accordingly, it is an object of this invention to provide an apparatus for use with multi-phase fluid systems wherein during operation an upper phase fluid may be automatically selectively removed from a portion of the surface of a lower phase fluid, while other portions of the surface remain covered with the upper phase fluid. It is another object of this invention to provide such an apparatus wherein, when the working operation is discontinued, the entire surface of the lower phase fluid is automatically completely covered with the upper phase fluid. It is another object to provide a process and apparatus for containing a multi-phase fluid system, wherein an article or material may enter and exit the lower phase fluid without contacting the upper phase fluid. It is still further object to provide such a system and apparatus wherein, during operation, the lower phase fluid may be continuously cleansed or scrubbed by the upper phase fluid.